This present invention relates to techniques for fabricating flat panel displays. More particularly, the invention is illustrated in an example related to the manufacture of an electro-optical element for use in, for example, inspecting flat panel displays, e.g., liquid crystal displays ("LCDs"), active matrix liquid crystal displays ("AMLCDs"), plasma displays, or the like. But it will be recognized that the invention also can be applied to the manufacture of almost any type electro-optical modulator material for a variety of applications.
The use of a flat panel display such as an active matrix liquid crystal display or the like continues to grow rapidly. For example, consumer items such as a pocket television, a notebook computer, an engineering work-station, a high-definition television, and others, use such a display. Based upon the continued demand for this display, industry has made massive capital investments in creating state-of-art manufacturing lines.
These state-of-art manufacturing lines, however, still rely in most part upon human test operators for the final test and inspection of these flat panel displays. The test operator performs a visual inspection of each display for defects in order to accept or reject the display. The quality or completeness of the inspection is dependent on the test operator, who has been trained using limited samples of displays that have defects and characterized as either pass or fail. The inspection results are highly subjective and prone to error, and cannot be used effectively and efficiently to monitor, control, and improve the quality of the various manufacturing processes.
Effective process monitoring and control of flat panel display production have been made possible through quantitative inspection methods by way of automatic inspection machines. An example of one of the first pioneering automatic inspection machines was developed by Photon Dynamics, Inc. ("PDI") in 1992, assignee of the present application. This first automatic inspection machine is pioneering, since a high quality inspection of flat panel displays could be performed using machines, rather than human test operators. This high quality inspection was performed on flat panel displays having completed thin film transistor components fabricated thereon.
The high quality inspection performed by machines occurs, in part, by way of conventional electro-optical elements. The electro-optical element is placed adjacent to, for example, an active matrix liquid crystal display substrate to be tested. When an electric field is impressed via the active matrix liquid crystal display upon the electro-optical element, optical properties of the element change. The change in optical properties is a microscopic optical change in the electro-optical element itself. Cameras read the change in the electro-optical element to identify defects in the active matrix liquid crystal display substrate being tested.
Although extremely useful, the conventional electro-optical element is generally difficult to manufacture. In particular, a relative complex sequence of manufacturing steps is generally performed to fabricate the electro-optical element. This complex sequence of steps generally causes lower yields and longer turn-around-times, which often lead to higher costs associated with manufacturing the element. Moreover, the conventional electro-optical element is extremely delicate and prone to damage, e.g., scratches, gouges. Damage to the element can occur even after the manufacturing process during use in the automated inspection process. Techniques have generally not been developed to easily repair the damaged electro-optical element. Accordingly, electro-optical elements are often replaced, which tends to further increase costs associated with the automated inspection process.
From the above, it can be seen that a technique for manufacturing or repairing electro-optical elements that is easy, cost effective, and reliable is often desirable.